rfc 2616 (rfc2616) - hypertext transfer protocol -- http-1_1.txt

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RFC 2616 (rfc2616) - Hypertext Transfer Protocol -- HTTP/1.1
RFC 2616 (RFC2616)
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Comment on RFC 2616 
RFC 2616 - Hypertext Transfer Protocol -- HTTP/1.1




Network Working Group                                      R. Fielding
Request for Comments: 2616                                   UC Irvine
Obsoletes: 2068                                              J. Gettys
Category: Standards Track                                   Compaq/W3C
                                                              J. Mogul
                                                                Compaq
                                                            H. Frystyk
                                                               W3C/MIT
                                                           L. Masinter
                                                                 Xerox
                                                              P. Leach
                                                             Microsoft
                                                        T. Berners-Lee
                                                               W3C/MIT
                                                             June 1999

                Hypertext Transfer Protocol -- HTTP/1.1

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   The Hypertext Transfer Protocol (HTTP) is an application-level
   protocol for distributed, collaborative, hypermedia information
   systems. It is a generic, stateless, protocol which can be used for
   many tasks beyond its use for hypertext, such as name servers and
   distributed object management systems, through extension of its
   request methods, error codes and headers [47]. A feature of HTTP is
   the typing and negotiation of data representation, allowing systems
   to be built independently of the data being transferred.

   HTTP has been in use by the World-Wide Web global information
   initiative since 1990. This specification defines the protocol
   referred to as "HTTP/1.1", and is an update to RFC 2068 [33].

Table of Contents

   1   Introduction ...................................................7
   1.1    Purpose......................................................7
   1.2   Requirements .................................................8
   1.3   Terminology ..................................................8
   1.4   Overall Operation ...........................................12
   2   Notational Conventions and Generic Grammar ....................14
   2.1   Augmented BNF ...............................................14
   2.2   Basic Rules .................................................15
   3   Protocol Parameters ...........................................17
   3.1   HTTP Version ................................................17
   3.2   Uniform Resource Identifiers ................................18
   3.2.1    General Syntax ...........................................19
   3.2.2    http URL .................................................19
   3.2.3    URI Comparison ...........................................20
   3.3   Date/Time Formats ...........................................20
   3.3.1    Full Date ................................................20
   3.3.2    Delta Seconds ............................................21
   3.4   Character Sets ..............................................21
   3.4.1    Missing Charset ..........................................22
   3.5   Content Codings .............................................23
   3.6   Transfer Codings ............................................24
   3.6.1    Chunked Transfer Coding ..................................25
   3.7   Media Types .................................................26
   3.7.1    Canonicalization and Text Defaults .......................27
   3.7.2    Multipart Types ..........................................27
   3.8   Product Tokens ..............................................28
   3.9   Quality Values ..............................................29
   3.10  Language Tags ...............................................29
   3.11  Entity Tags .................................................30
   3.12  Range Units .................................................30
   4   HTTP Message ..................................................31
   4.1   Message Types ...............................................31
   4.2   Message Headers .............................................31
   4.3   Message Body ................................................32
   4.4   Message Length ..............................................33
   4.5   General Header Fields .......................................34
   5   Request .......................................................35
   5.1   Request-Line ................................................35
   5.1.1    Method ...................................................36
   5.1.2    Request-URI ..............................................36
   5.2   The Resource Identified by a Request ........................38
   5.3   Request Header Fields .......................................38
   6   Response ......................................................39
   6.1   Status-Line .................................................39
   6.1.1    Status Code and Reason Phrase ............................39
   6.2   Response Header Fields ......................................41

   7   Entity ........................................................42
   7.1   Entity Header Fields ........................................42
   7.2   Entity Body .................................................43
   7.2.1    Type .....................................................43
   7.2.2    Entity Length ............................................43
   8   Connections ...................................................44
   8.1   Persistent Connections ......................................44
   8.1.1    Purpose ..................................................44
   8.1.2    Overall Operation ........................................45
   8.1.3    Proxy Servers ............................................46
   8.1.4    Practical Considerations .................................46
   8.2   Message Transmission Requirements ...........................47
   8.2.1    Persistent Connections and Flow Control ..................47
   8.2.2    Monitoring Connections for Error Status Messages .........48
   8.2.3    Use of the 100 (Continue) Status .........................48
   8.2.4    Client Behavior if Server Prematurely Closes Connection ..50
   9   Method Definitions ............................................51
   9.1   Safe and Idempotent Methods .................................51
   9.1.1    Safe Methods .............................................51
   9.1.2    Idempotent Methods .......................................51
   9.2   OPTIONS .....................................................52
   9.3   GET .........................................................53
   9.4   HEAD ........................................................54
   9.5   POST ........................................................54
   9.6   PUT .........................................................55
   9.7   DELETE ......................................................56
   9.8   TRACE .......................................................56
   9.9   CONNECT .....................................................57
   10   Status Code Definitions ......................................57
   10.1  Informational 1xx ...........................................57
   10.1.1   100 Continue .............................................58
   10.1.2   101 Switching Protocols ..................................58
   10.2  Successful 2xx ..............................................58
   10.2.1   200 OK ...................................................58
   10.2.2   201 Created ..............................................59
   10.2.3   202 Accepted .............................................59
   10.2.4   203 Non-Authoritative Information ........................59
   10.2.5   204 No Content ...........................................60
   10.2.6   205 Reset Content ........................................60
   10.2.7   206 Partial Content ......................................60
   10.3  Redirection 3xx .............................................61
   10.3.1   300 Multiple Choices .....................................61
   10.3.2   301 Moved Permanently ....................................62
   10.3.3   302 Found ................................................62
   10.3.4   303 See Other ............................................63
   10.3.5   304 Not Modified .........................................63
   10.3.6   305 Use Proxy ............................................64
   10.3.7   306 (Unused) .............................................64

   10.3.8   307 Temporary Redirect ...................................65
   10.4  Client Error 4xx ............................................65
   10.4.1    400 Bad Request .........................................65
   10.4.2    401 Unauthorized ........................................66
   10.4.3    402 Payment Required ....................................66
   10.4.4    403 Forbidden ...........................................66
   10.4.5    404 Not Found ...........................................66
   10.4.6    405 Method Not Allowed ..................................66
   10.4.7    406 Not Acceptable ......................................67
   10.4.8    407 Proxy Authentication Required .......................67
   10.4.9    408 Request Timeout .....................................67
   10.4.10   409 Conflict ............................................67
   10.4.11   410 Gone ................................................68
   10.4.12   411 Length Required .....................................68
   10.4.13   412 Precondition Failed .................................68
   10.4.14   413 Request Entity Too Large ............................69
   10.4.15   414 Request-URI Too Long ................................69
   10.4.16   415 Unsupported Media Type ..............................69
   10.4.17   416 Requested Range Not Satisfiable .....................69
   10.4.18   417 Expectation Failed ..................................70
   10.5  Server Error 5xx ............................................70
   10.5.1   500 Internal Server Error ................................70
   10.5.2   501 Not Implemented ......................................70
   10.5.3   502 Bad Gateway ..........................................70
   10.5.4   503 Service Unavailable ..................................70
   10.5.5   504 Gateway Timeout ......................................71
   10.5.6   505 HTTP Version Not Supported ...........................71
   11   Access Authentication ........................................71
   12   Content Negotiation ..........................................71
   12.1  Server-driven Negotiation ...................................72
   12.2  Agent-driven Negotiation ....................................73
   12.3  Transparent Negotiation .....................................74
   13   Caching in HTTP ..............................................74
   13.1.1   Cache Correctness ........................................75
   13.1.2   Warnings .................................................76
   13.1.3   Cache-control Mechanisms .................................77
   13.1.4   Explicit User Agent Warnings .............................78
   13.1.5   Exceptions to the Rules and Warnings .....................78
   13.1.6   Client-controlled Behavior ...............................79
   13.2  Expiration Model ............................................79
   13.2.1   Server-Specified Expiration ..............................79
   13.2.2   Heuristic Expiration .....................................80
   13.2.3   Age Calculations .........................................80
   13.2.4   Expiration Calculations ..................................83
   13.2.5   Disambiguating Expiration Values .........................84
   13.2.6   Disambiguating Multiple Responses ........................84
   13.3  Validation Model ............................................85
   13.3.1   Last-Modified Dates ......................................86

   13.3.2   Entity Tag Cache Validators ..............................86
   13.3.3   Weak and Strong Validators ...............................86
   13.3.4   Rules for When to Use Entity Tags and Last-Modified Dates.89
   13.3.5   Non-validating Conditionals ..............................90
   13.4  Response Cacheability .......................................91
   13.5  Constructing Responses From Caches ..........................92
   13.5.1   End-to-end and Hop-by-hop Headers ........................92
   13.5.2   Non-modifiable Headers ...................................92
   13.5.3   Combining Headers ........................................94
   13.5.4   Combining Byte Ranges ....................................95
   13.6  Caching Negotiated Responses ................................95
   13.7  Shared and Non-Shared Caches ................................96
   13.8  Errors or Incomplete Response Cache Behavior ................97
   13.9  Side Effects of GET and HEAD ................................97
   13.10   Invalidation After Updates or Deletions ...................97
   13.11   Write-Through Mandatory ...................................98
   13.12   Cache Replacement .........................................99
   13.13   History Lists .............................................99
   14   Header Field Definitions ....................................100
   14.1  Accept .....................................................100
   14.2  Accept-Charset .............................................102
   14.3  Accept-Encoding ............................................102
   14.4  Accept-Language ............................................104
   14.5  Accept-Ranges ..............................................105
   14.6  Age ........................................................106
   14.7  Allow ......................................................106
   14.8  Authorization ..............................................107
   14.9  Cache-Control ..............................................108
   14.9.1   What is Cacheable .......................................109
   14.9.2   What May be Stored by Caches ............................110
   14.9.3   Modifications of the Basic Expiration Mechanism .........111
   14.9.4   Cache Revalidation and Reload Controls ..................113
   14.9.5   No-Transform Directive ..................................115
   14.9.6   Cache Control Extensions ................................116
   14.10   Connection ...............................................117
   14.11   Content-Encoding .........................................118
   14.12   Content-Language .........................................118
   14.13   Content-Length ...........................................119
   14.14   Content-Location .........................................120
   14.15   Content-MD5 ..............................................121
   14.16   Content-Range ............................................122
   14.17   Content-Type .............................................124
   14.18   Date .....................................................124
   14.18.1   Clockless Origin Server Operation ......................125
   14.19   ETag .....................................................126